Honing tools and method



March 26, 1968 w. MATTHEW HONING TOOLS AND METHOD 2 SheetsSheet 1 Filed Jan. 28, 1966 Fig. 1

25.55:5&Q

I/VVENTOR.

// @af/ew United States Patent 3,374,516 HONING TOOLS AND METHOD Windell Matthew, Rte. 1, Campbelisburg, Ind. Filed Jan. 28, 1966, Ser. No. 523,751 14 Claims. (Cl. 29-76) This invention relates generally to machine tools and more particularly to honing machines, and new apparatus and a method for use thereof whereby honing operations can be speeded up and tool life is extended.

Honing machines are well known in the machine tool part and are commonly used for sizing and finishing cylindrical surfaces, and primarily internal cylindrical surfaces. One use of the honing process is in the finishing of the inside of comparatively long pipes or tubes such as gun barrels or hydraulic cylinders.

A honing tool typically employs three or more bonded abrasive sticks or stones mounted in holders and expanded outwardly with respect to a rotational axis, to work on the bore being finished. In contrast to a drilling or boring process, wherein the cutting tool describes a fixed path on the surface of a cylinder, the center of which is definitely determined by the position of the boring bar spindle, the honing tool is free to align and center itself within a rough finished bore. The honing tool is rotated and reciprocated in the bore, and as the operation proceeds the honing sticks are forced out radially from the center of the tool.

Often it happens that an excessive amount of stock must be removed from the inside of cylinders and tubing, and the result is excessive Wear of the stones. In addition to this, the process is comparatively slow, and this factor, together with the rapid wear of comparatively expensive stones, underlines the desirability of better apparatus and methods.

It is therefore a general object of the present invention to provide a honing apparatus and method for materially increasing the speed of the honing process, and materially reducing the cost thereof.

It is a further object to provide an apparatus and method which can be practiced without extensive modification of existing honing machine components and which, therefore, can be implemented easily.

Described briefly, in a typical embodiment of the present invention, conventional honing sticks are replaced by steel sticks or bars having cutting teeth and bearing surfaces thereon. The cutting teeth eifect rapid stock removal without generating objectionable surface finish features, and the bearing surfaces control the depth of cut.

The full nature of the invention will be understood from the accompanying drawings and the following description and claims:

FIGURE 1 is a schematic elevational view illustrating a honing machine with the work mounted thereon ready for processing, this view being on a very small scale.

FIGURE 2 is an enlarged view of a honing tool, shown partially in section, and incorporating honing sticks according to a typical embodiment of the present invention.

FIGURE 3 is a top plan view of a honing stick according to a typical embodiment of the present invention and shown on a greatly enlarged scale.

FIGURE 4 is an end view of a honing tool incorporating six such sticks and working in a cylinder.

FIGURE 5 is a fragmentary sectional view through a cylinder with a pair of honing sticks according to the resent invention shown in diametrically opposed relationship, and illustrating one function of the bearing surfaces.

FIGURE 6 schematically shows, on a small scale, six different possible arrangements of teeth on the honing sticks according to the present invention.

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Referring now to the drawings in detail, and FIGURE 1 in particular, the honing machine includes a base 11 on which a cylindrical tube 12 is secured by clamps 13 and 14. This tube is the wor' which is to be processed by the honing machine, for finishing the cylindrical bore thereof.

The honing tool 16 is mounted at the front end of a long arbor 17 which is driven by a motor 18 for rotating the tool in the work. The motor and arbor are mounted on a carriage 19 reciprocable in the direction of the arrows 21 and 22 for moving the honing tool through the work and out. A motor and gear arrangement or some other means 23 can be used for reciprocating the tool as required.

Referring now to FIGURE 2, the illustrated honing tool has a body 24 supporting a plurality of honing stick holders, two of these holders 26 being shown. Expanders 27 are provided between the tool body axis 28 and the holders 26, and are movable radially outward by advancing the double cone assembly 29 relative to the body 24 along axis 28 in the direction of the arrow 21. The cone 29 can be advanced with respect to the tool body by any suitable means in the combination expander and universal joint assembly 31. These are conventional components and are well known. For example, expansion can be accomplished by spring pressure on the cone assembly, by screw action that advances the cone when braking action is applied to an outer sleeve, or by hydraulic pressure on a piston. The universal joint assembly permits the tool to align itself with the bore so that, in etfect, it floats, and the tool body axis 28 need not be colinear with the arbor axis 28a and need not even intersect it if the universal joint is sufiiciently flexible.

To keep the holders against the expande-rs, and keep them in the grooves (FIGURE 4) 32 between the segments-33 of the drive web or flange portion of the tool body, garter springs or wires 34 are provided in slots 36 in the ends of the holders.

In the example illustrated in FIGURE 2, the honing sticks 37 of the present invention are secured in the holders by set screws 38, but any other suitable means such as adhesives, clamps, or other devices can be em ployed to serve this purpose. FIGURE 3 is a very much enlarged top view of one of these sticks 37 and FIGURE 5 shows two of these sticks in diametrically opposed relationship as they would be on a four or six stone honing tool body, for example.

Referring now to FIGURE 3, two sets of teeth'are provided on the top side of the stick or bar, while the bottom and the two vertical sides of the bar are comparatively smooth and fiat. Teeth 40 have their cutting edges facing toward the rear end 39 of the bar as shown in FIGURE 5, and teeth 41 have their cutting edges facing toward the front end 42 of the bar. It would appear, therefore, that as the honing tool is moved through the tube 12 in the direction of the arrow 21, teeth 41 would do all of the cutting and teeth 40 would do no cutting and would tend to be dulled. However, the angle at which the teeth are set, and the rotational speed may be selected so that the teeth 40 are also cutting and moving against the tube in a cutting direction rather than a dragging direction, if desired.

For example, it is clear that if the tool is advancing linearly in the direction of the arrow 21 and is rotating so that the portion above the rotational axis 28 (FIGURE 2) moving in the direction of the arrow 43, the teeth 41 will be moving in a cutting sense relative to the bore of the tube 12. However, if there were no rotation, the teeth 40 would be moving in a dragging or sliding sense relative to the bore of the tube.

Now, consider a point 44 at the crest of one of the teeth 40, the crest being -a point on the cutting edge; This point will be cutting if the actual direction of its motion in space is to the rear of a plane 46 containing the cutting edge of the tooth and containing a radius from the point 44 through the axis :28. Therefore, if the length of the arrow 47 represents the linear speed of pushing the tool through the tube (the feed stroke speed) and the length of arrow 48 represents the speed of the tooth at point 44 which is caused by rotation of the honing tool, the actual movement of point 44 with respect to the tube surface is represented by arrow 49 and its speed is represented by the length of the arrow 49. So long as the angle B between the actual direction of the point 44 and the direction of advance of the honing tool is greater than the angle C between the cutting edge of the tooth 40 and the direction of linear movement of the honing tool, the point 44 will be moving in a cutting sense with respect to the bore of the tube.

Another important feature of the invention is the pro vision of bearing surfaces on the top of each stick or bar. On bar 37, bearing surfaces are provided at 51, 52, and 53. As shown in FIGURE 5, the crests of the teeth 40 and 41 are at a level 54. The roots or bases of the teeth are at a level 56. The bearing surfaces are at a level 57 which is between the levels 54 and 56. The distance of the hearing surface below the tooth edge or crest level is selected to provide the maximum depth of cut desired. As an example, this might be four thousandths of an inch. Therefore, when the honing tool enters the rear end 58' of work (FIGURE 1) the bearing surfaces 51 will prevent the leading teeth of .the group 40 from cutting too deeply. Then, after the honing tool has been pushed through the tube until the front portion thereof has been pushed out the front end 59 thereof the intermediate and rear bearing surfaces 52 and 53, respectively, cooperate to prevent the rear teeth of set 41 from gouging or cutting too deeply.

As shown in FIGURE 4, which is illustrative of a six stone holder assembly, .thebars have the tooth crests and bearing surfaces rounded as shown so that the corners 61 are rounded and the portion 62 is also rounded. The radius of the curve 62 on the tooth edges can be selected as desired, and one possibility is to make the radius equal to the radius of the rough bore of the work to be processed. Likewise, the bearing surfaces can be rounded as shown for bearing surface 51 in FIGURE 4.

FIGURE 6 shows various possible arrangements and combinations of teeth and tooth angles. Feed and speeds are selected so that the teeth do not try to screw into the bore. It may be desirable in certain instances with certain specific honing bars to have the feedand speeds about the same as would be used with conventional honing stones. The material used in the bars is typically high speed tool steel and the finished tooth contours and bearing surfaces can be achieved by grinding.

From the foregoing description, it will be apparent that the present invention provides for many possible combinations of tooth angles, process feeds and speeds, cut ting edge and bearing surface materials, as well as enabling rapid processing of work, achievement ofa variety of surface finishes, and reduction of tooling and labor costs. The same rotational direction and speed are normally used for both the forward and back stroke of the tool through the work, according to the present invention.

As suggestedby the first of the six different tools shown in FIGURE -6, middle bearing surface areas 58 may be ground where teeth have been cut, and the overall middle bearing surface area will include some remnants of the grooving which results from the cutting of the teeth. If this is desired rather than a perfectly smooth central bearing surface, such as is provided at the surfaces 51 and 53, one can recognize that during advance of the tool through the tube, teeth 41 would work like cutting tools, while the central bearing surface 52 mightwork like a mill file, and the teeth 40 might work like a reamer. Then, on the back stroke, the action of the teeth is reversed and the central bearing surface still works like a 1. In a honing machine, the combination comprising:

an elongated bar;

a plurality of outwardly projecting'teeth along the top of said bar;

a plurality of bearing surfaces on the top of said bar, said bearing surfaces being at a level below the crests of said teeth but above the bases of said teeth.

2. The combination of claim 1 and further comprising:

a holder receiving said bar and receivable in a tube to be honed and arranged to urge said top of said bar outwardly against the bore of the tube,

said bearing surfaces being arranged to bear on the bore of the tube when the tool projects partly out of the bore, to thereby avoid excessive and irregular cutting of the bore.

3. The honing tool of claim 1 wherein:

said bearing surfaces are spaced apart along said bar;

4. The honing tool of claim 1 wherein: two of said bearing surfaces are adjacent ends of said bar, and one of said bearing surfaces is intermediate the ends of said bar.

5. The honing tool of claim 1 wherein said bearing surfaces are at a level of less than five thousandths of an inch below the crests of said teeth.

6. The combination of claim 1 wherein:

said teeth are arranged in first and second groups, with the cutting edges of the teeth in said first group being aligned along parallel lines disposed at an acute angle with respect to a side of said bar, and the cutting edges of the teeth in said second group being aligned along parallel lines disposed at an obtuse angle with respect to said side of said bar.

7. The combination of claim 6 wherein:

said cutting edges face generally toward a point equidistant between the ends of said bar. v 8. The combination of claim 6 and further comprising: means driving said bar in unidirectional rotation and in forward and reverse strokes and at rotational speed effecting cutting action of the teeth of both groups against a work surface during both forward and reverse strokes.

'9. The combination of claim 1 and further comprising:

a first holder receiving said bar and receivable in a tube to be honed, and arranged to urge said teeth out wardly against the bore of the tube,

a 'body having a plurality of holders therein like said first holder and a plurality of bars mounted in said holders like said first bar is mounted in said first holder,

means in said body for urging said holders and thereby said bars outwardly to engage the teeth of all bars with said tube bore.

10. The combination of claim 9 and further comprising:

drive coupling means conected to said body and driving body in one rotational direction as said body is moved in and out in said tube. 12. The combination of claim 1 and further comprising:

an arbor; a motor driving said arbor in rotation; and a plurality of bars in addition to said bar and like said bar and floatingly mounted to said arbor for following the contour of the Work during rotation of said arbor; and reciprocating means coupled to said arbor for reciprocating said bars in a direction generally parallel to the axis of rotation of said arbor. 13. A method of finishing the interior of a tube comprising the steps of:

advancing a toothed cutting tool in a spiral path through said tube and simultaneously cutting material from the bore of said tube with said tool;

6 retracting said tool in another spiral path through said tube and rotating said tool during retraction in the same direction as said tool is rotated during advancement whereby the path followed during retraction crosses the path followed during advancement, cutting material from the bore with said tool simultaneously with the retracting of said tool; and supporting the tool by means of the tube during advancement and retraction whereby the tool follows the tube bore. 14. The method of claim 13 and further comprising the step of controlling the depth of cut by resting smooth portions of said tool on said bore.

No references cited.

HARRISON L. HINSON, Primary Examiner. 

1. IN A HONING MACHINE, THE COMBINATION COMPRISING: AN ELONGATED BAR; A PLURALITY OF OUTWARDLY PROJECTING TEETH ALONG THE TOP OF SAID BAR; 